Present invention relates to a digital camera, and more particularly, to a digital camera equipped with an image display section.
In the case of a conventional digital camera of a popularized type, a CCD having 300,000–400,000 pixels has been used as an image pickup element, and therefore, image data have been with about 640×480 pixels.
For the foregoing, however, a digital camera employing a CCD with 1,000,000 or more pixels has made it appearance in recent years, and image data with 1280×1000 pixels or more have become relatively inexpensive.
As a trend toward higher number of pixels advances, image data grow greater in amount, which requires operation to compress, for the storage purpose, the images picked up, and requires much time for the operation conducted to reproduce the recorded image data.
For making data amount to be small without sacrificing resolution, there have been proposed some systems as an image file format standard (Exif) of a digital still camera. The term “Exif” means a file format to regulate so as to memorize simultaneously information regarding F-No. of a camera, a shutter speed and etc. when data are compressed in accordance with JPEG.
Some of the image file formats are shown in FIG. 2. In FIG. 2, an area surrounded by each frame is assumed to correspond to one pixel in image pickup (sampling).
FIG. 2(a) shows one wherein R, G and B are sampled equally in each pixel, and it is an image file format called RGB 4:4:4. Here, sampling is conducted by detecting luminance components and color components equally. In this case, data tend to be large in amount though also colors are reproduced with fidelity.
FIG. 2(b) shows one for sampling luminance (Y) components and color difference (Cr (Y−R), Cb (Y−B)) components, and for sampling further color difference components on a point-sequential basis, and it is an image file format called YCbCr 4:2:2. Here, the sampling is conducted by detecting luminance components on all pixels and by detecting color difference components on a point-sequential basis, which is characterized that data can be made small in amount though color reproduction is somewhat sacrificed, in this case.
FIG. 2(c) shows one for sampling color difference on a point-sequential basis and on a line-sequential basis concerning luminance (Y) components and color difference (Cr (Y−R), Cb (Y−B)) components, and it is an image file format called YCbCr 4:2:0. Here, the sampling is conducted by detecting luminance components on all pixels and by detecting color difference components on a point-sequential basis and on a line-sequential basis, which is characterized that data can further be made small in amount though color reproduction is sacrificed, in this case.
Incidentally, since compression is made by a block of 8×8 pixels, the number of pixels in the lateral direction is a multiple of 16 and the number of pixels in the longitudinal direction is a multiple of 8, which is prescribed in the stipulation of Exif.
In the case of a digital camera, there are some image file formats as stated above, and the number of pixels of image data varies depending on the type of the camera.
Accordingly, image data obtained by photographing with various digital cameras can be read by a computer, but there has been no consideration for utilization of image data between digital cameras each being different in type.
Namely, even in the case where a common memory card can be used between digital cameras each being different, there has been a problem that an image obtained through photographing by a certain digital camera can not be reproduced on a display of another digital camera.